The proposed studies are designed to test the hypothesis that accumulation of neurotransmitters by rat brain synaptic vesicles is transmitter-specific. Using procedures developed in this laboratory to a) extend the period of synaptic vesicle inability to several hours at 37 degrees, b) observe selective accumulation of 3H-NE, Da gaba and glutamate, and c) immobilize vesicles for continual monitoring of transmitter fluxes, the following studies will be accomplished; The neurotransmitter profile examined will be expanded to include 5HT. Selectivity of vesicular transmitter uptake will be verified using enriched vesicle populations, denervation studies and vesicle fractionation techniques. Biochemical and mechanistic studies to characterize the transport and afflux of each of the five neurotransmitters will be performed. These studies will include a survey of stereochemical requirements for drug interaction with vesicular transport of NE, DA, and 5HT. Selective drugs/vesicle interactions will be examined. The studies are designed to establish a foundation for assessing the role of the synaptic vesicle in central neurotransmission.